1. Field of the Invention
This invention relates to a gang head means for a replaceable gang head type machine tool and more particularly, to a gang head for a machine tool which can be moved at an inclined angle with respect to a workpiece.
2. Description of the Prior Art
In prior art machine tools such as shown in FIG. 1, for example, a machine base A has a driving unit C mounted thereon, which is movable to advance and retract to and from a jig table B located in front thereof. An annular rail means F comprising a pair of upper and lower annular rails, each surrounding the driving unit C includes a rear stationary rail D and a front movable rail E movable to advance and retract together with the driving unit C. A plurality of gang head means are mounted on the annular rails F and any desired one of them may be positioned on the upper and lower movable rails E by turning an index table I, and advancing the driving unit C. The gang head means selected on the movable rails E is advanced together with the movable rails E towards a workpiece W on the jig table B and the workpiece W is worked by the gang head means.
It has been usual with this type machine tool that the gang head means has a mounting base frame a with a coupling b on its rear surface, the coupling b being connected to a driving shaft G on a front surface of the driving unit C. A multiple spindle type working unit d having a gear box c and arranged to be driven by a power inputted from the coupling b is on a front surface of the mounting base frame a such that its movement in the axial direction may extend along the advancing and retracting directional lines of the movable rails E. By an advancing movement of the rails E, drilling or any other working operation may be carried out on a surface of the workpiece W that is at right angles to the advancing and retracting directions of the movable rails E.
Consequently, any desired working on the surface of the workpiece E which is at right angles to the advancing and retracting directional lines of the movable rails E can be carried out by positioning any desired one of various types of gang head means on the movable rails E. However, any working on an inclined surface of the workpiece E that is not at right angles to the advancing and retracting direction of the movable rails E can not be performed.
In theory, a working unit of the above type may be attached to the frame base a so that its axial direction may be inclined to the advancing and retracting direction of the movable rails E, and also the working unit may be arranged to be movable to advance and retract in its axial direction. Thus, after the movable rails E are advanced to a predetermined position, the working unit d is advanced in its axial direction so that the inclined surface of the workpiece W may be worked thereby. However, for achieving this, a problem arises in how to transmit power from the driving unit C to the working unit arranged to be movable to advance and retract in the inclined direction.
The problem is particularly bad in a case where plural working units are attached to the mounting frame base a so that their inclined directions may be different from each other for applying simultaneous workings to plural inclined surfaces of the workpiece W. If power is mechanically transmitted through a gear means to each of the working units, the transmission mechanism becomes complicated and large in size, and mounting thereof on the mounting frame base a becomes difficult.